<template>
  <div class='xtx-carousel' @mouseenter="stop()" @mouseleave="start()">
    <ul class="carousel-body">
      <li class="carousel-item" v-for="(item,i) in sliders" :key="i" :class="{fade:index===i}">
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="">
        </RouterLink>
      </li>
    </ul>
    <a @click="toggle(-1)" href="javascript:;" class="carousel-btn prev"><i class="iconfont icon-angle-left"></i></a>
    <a @click="toggle(1)" href="javascript:;" class="carousel-btn next"><i class="iconfont icon-angle-right"></i></a>
    <div class="carousel-indicator">
      <span @click="index=i" v-for="(item,i) in sliders" :key="i" :class="{active:index===i}"></span>
    </div>
  </div>
</template>

<script>
import { ref, watch } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    sliders: {
      type: Array,
      default: () => []
    },
    duration: {
      type: Number,
      default: 2
    },
    autoplay: {
      type: Boolean,
      default: false
    }
  },
  setup(props) {
    // 设置默认显示的图片的索引
    const index = ref(0)
    // 自动播放方法，用定时器来控制轮播组件，每过duration/单位秒
    // 就让index++,用条件判断不让它超过轮播图个数，控制index和返回的轮播图数组数据下标相等来控制样式fade
    // 这样就实现了轮播的效果
    let timer = null
    const autoplayFn = () => {
      clearInterval(timer)
      timer = setInterval(() => {
        index.value += 1
        if (index.value >= props.sliders.length) {
          index.value = 0
        }
      }, props.duration * 1000)
    }
    // 侦听器，侦听到父组件传递进来图片数据了就触发方法开始轮播
    watch(
      () => props.sliders,
      newVal => {
        if (newVal.length > 1 && props.autoplay) {
          autoplayFn()
        }
      },
      { immediate: true }
    )
    // 鼠标进入轮播图区域轮播图停止轮播
    const stop = () => {
      if (timer) clearInterval(timer)
    }
    // 鼠标离开轮播图区域轮播图开始轮播
    const start = () => {
      // autoplayFn()
      if (props.sliders.length > 1 && props.autoplay) {
        autoplayFn()
      }
      // if (props.sliders.length && props.autoPlay) {
      //   autoplayFn()
      // }
    }
    // 点击左右切换上一张下一张
    const toggle = step => {
      index.value += step
      if (index.value >= props.sliders.length) {
        index.value = 0
        return
      }
      if (index.value < 0) {
        index.value = props.sliders.length - 1
      }
    }
    return { index, stop, start, toggle }
  }
}
</script>
<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>
